Before a general electronic device starts to operate, it requires a certain waiting time for the power source to raise to a stable state. Thereby, an electronic device will make use of the waiting time for initialization such as resetting. Currently, one reset method is to use a reset circuit formed by a resistor, a capacitor, and a schmitt trigger to generate a reset signal. Nonetheless, in the method, if the power source needs a longer time to reach the normal stable state, resetting might have been ended by the reset circuit before the power source reaches the normal stable state and hence leading to operational error. In addition, if the power source of an electronic device appears rapid power down, the electronic device should be reset.
Unfortunately, when modern electronic devices are reset, the state of the power source is not detected. The state of the power source is not confirmed to reach normal and stable before the resetting ends. Besides, electronic devices do not detect occurrence of rapid power down for resetting. As a consequence, normal operations of electronic devices cannot be guaranteed.
Accordingly, the present invention provides a detection circuit for detecting the state of the power source.